East China Sea: Tropical Depression Chanthu tracking southeastward in East China Sea Sept. 15 /update 2

Event

Tropical Depression Chanthu is tracking slightly southeastward but remains largely stationary in the East China Sea Sept. 15. As of 03:00 KST, the storm's center of circulation was approximately 519 km (322 miles) southwest of Sasebo, Japan.

Forecast models indicate the storm is likely to remain largely stationary in the East China Sea through early Sept. 16. Chanthu is then likely to turn north-northeastward and dissipate as a post-tropical cyclone over water by early Sept. 17 as it makes a close approach to Jeju Island, South Korea. The storm's track and intensity forecast remain uncertain, and the system may change accordingly over the coming days.

Government Advisories
As of Sept. 15, the China Meteorological Administration has issued a blue typhoon warning in connection with Chanthu, warning that strong winds are forecast for the central and southern Yellow Sea, the East China Sea, the northern coast of Zhejiang Province, coastal Shanghai, the southern coast of Jiangsu Province, Hangzhou Bay, and the Yangtze River estuary area.

The Japan Meteorological Agency has issued the following advisories:

• Yellow (lowest level on a four-tier scale) landslide advisories due to heavy rain: Tanegashima and Yakushima, Kagoshima Prefecture

The Korean Meteorological Administration has issued a typhoon warning for parts of Jeju Island and the waters off the country's southwestern and southern coasts.

Authorities will likely issue new warnings or update existing advisories throughout the system's progression in the coming days. Weather warnings could remain active even after the system's immediate threat has diminished, as some areas may still be highly susceptible to rain-induced hazards. The possibility of localized evacuations cannot be discounted if weather conditions prove particularly hazardous.

Hazardous Conditions
The storm may bring heavy rainfall, strong winds, and rough seas over the coming days to parts of Jeju Island, South Korea; Nagasaki, Kumamoto, and Kagoshima prefectures, Japan; and eastern China. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and urban areas with easily overwhelmed or a lack of stormwater drainage systems.

Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall. Rain-induced landslides are possible in steeply sloped terrains. Flooding could isolate some communities for several days. Prolonged swells and storm surge generated by the system will likely result in coastal flooding. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments.

Transport
Inclement weather associated with the storm could trigger localized business, transport, and utility disruptions. Floodwaters and debris flows could render some bridges or roadways impassable, impacting overland travel in and around affected areas. Areal flooding in urban locations could also result in severe traffic congestion, while strong winds will pose a hazard to high-profile vehicles. Heavy rain and low visibility may trigger flight disruptions at regional airports.

Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after weather conditions have improved. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Health
Stagnant pools of water during and after flooding increase the incidence of insect- and waterborne diseases, such as dengue fever, cholera, and malaria. The threat of these disease outbreaks is usually elevated in the low-income or underdeveloped areas of major urban centers due to the presence of incomplete or open sewer lines. The latent threat of waterborne contaminants from inundated industrial sites cannot be discounted; exposure to raw sewage and other hazardous materials mixed with floodwaters poses a serious health threat.

Advice

Activate contingency plans in areas where officials forecast tropical weather conditions. Heed any evacuation orders that may be issued. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the potential for severe flooding and storm surge. Stockpile water, batteries, and other essentials in advance. Charge battery-powered devices when electricity is available; restrict the use of cellular phones to emergencies only. Power down mobile devices when not in use. Keep important documents and necessary medications in waterproof containers. Observe strict food and water precautions, as municipalities could issue boil-water advisories following flooding events. Take precautions against insect- and waterborne diseases in the coming weeks.

Plan accordingly for protracted commercial, transport, and logistics disruptions in areas in the path of the storm, especially if vital infrastructure is damaged. Seek updated information on road conditions before driving or routing shipments through areas where flooding has occurred. Confirm flights before checking out of hotels or driving to the airport; clearing passenger backlogs may take several days in some locations.

Resources

Joint Typhoon Warning Center
Taiwan Central Weather Bureau
China Meteorological Administration (Mandarin)
Japan Meteorological Agency (Japanese)
Korea Meteorological Administration (Korean)